A molding process which is called "a transfer molding process" for press-fitting resin plasticized in a pot through a runner into the cavity of a mold under high pressure at high temperature has been employed in general to package a semiconductor device and the like. This process must firmly retain a terminal of the semiconductor device which is extended outside in the mold so as not to externally lead the resin. Since the resin is press-fitted into the mold under very high pressure such as several tens tons, the mold of very high accuracy is required. In addition, in order to mold with reasonable expenses, a large number of semiconductor devices must be simultaneously molded, resulting in a large scale of mold of high cost. Therefore, this process is not appropriate except for a small type and large quantity production. However, the types of semiconductor devices to be used for a limited utility have been recently increased, and trial production necessitates only small quantity. To this end, it is improper to employ the abovementioned transfer molding process. Thus, a simple packaging method for semiconductor devices for a multiple kind and small quantity production instead of the prior process has been desired.
A process for sealing a chip by preparing a pair of packages of complete product which is eventually molded in advance and interposing and sealing the chip bonded on a lead frame between the pair of packages has been proposed to respond to this requirement.
According to this proposed process, a large-scale mold is not necessary, but since the packages used in this process is made of thermoplastic resin, a difficulty arises in bonding between.the packages, thereby causing the chips not to be completely sealed and hardly preventing the dies used from oxidizing. Therefore, a novel packaging method and apparatus has been required so as to solve these drawbacks in this process.